1. Field of The Invention
The present invention relates to an electrical cable, and particularly to an electrical cable which provides an improved shielding means.
2. Description of Prior Art
With the development of computer technology, a new product, named as a serial ATA electrical connector, is developed for use as an interface of fast-talking drives, which will effectively double the bandwidth, or capacity for data, between disk drivesxe2x80x94-ranging from hard drives to CD-rewritable drivesxe2x80x94-and other PC components. Referring to FIG. 3, such a serial ATA cable 3 for signal transmission comprises twin axial or parallel pair cable subassemblies 32. Each cable subassembly 32 includes a pair of insulated signal conductors 34 and a pair of non-insulated grounding drain wires 36 besides the two signal conductors 34, all of which are arranged side by side as shown, and all of the signal conductors 34 and drain wires 36 fall on a common plane 30. A layer of conductive shielding 38 is wrapped around the pair of signal conductors 34 and drain wires 36 so that it is in electrical contact with the drain wires 36. An optional jacket 39 is covered over the pair of shieldings 38. The shielding 38 prevents emissions from the cable 3 as well as provides isolation from nearby or stray signals, and the planar structure of the cable provides advantages in routing and other cable management tasks for certain applications. However, the pair of cable subassemblies 32 are isolated from each other by a portion of the jacket 39, and the number of the drain wires 36 adapted for grounding are comparatively too many, thereby resulting in an increase in the whole width of the electrical cable 3 and complicating the manufacturing process of the cable 3 as well.
Hence, an improved shielded cable is required to overcome the disadvantages of the prior art.
A main object of the present invention is to provide an electrical cable having relative reduced whole width and low cost while providing an effective grounding function.
An electrical cable for signal transmission comprises a pair of signal transmission groups, a single non-insulated first drain wire sandwiched between adjacent inner sides of the signal transmission groups and a pair of non-insulated second drain wires disposed at opposite outer sides of the transmission groups. Each signal transmission group has a pair of insulated signal conductors and a layer (15) of shielding, made of aluminum foil or the like, surrounding on the insulated signal conductors. Both the first and second drain wires are electrical contacted with associated outside surfaces of the layers of shielding for providing a grounding circuit. All of the signal conductors and the first and second drain wires are arranged side by side and their axes fall on a common plane. An optional jacket is wrapped on the signal transmission groups and the first and second non-insulated drain wires.
Other objects, advantages and novel features of the invention will more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings.